Door Hinges Brass Coated with ?

Greetings, I picked up a box of old Russwin hinges which I believe to be solid brass. However, they're covered with a dark film which may be some sort of varnish.

So my questions are:
When an item is described as 'solid brass' is it really 100% brass or brass colored over pot metal?
How can I tell if these hinges are solid brass? They're not ferrous but that's as far as I've gotten.
Is the dark film a varnish originally applied to keep the brass from darkening?
Should I try and remove the film to determine if it's shellac or varnish?

Thanks, and let me know if this should be posted in another forum.

 

This seller calls it "honest patina."

https://placemakersinc.com/product/heavy-brass-russwin-hinges-4-5x4-5/

Debora

 

They are certainly not pot metal, which wouldn't begin to carry the load or do the job those hinges were designed an' made to do. Russwin was/is high quality goods, which should be obvious to the most casual observer.

 

Could have been coated with lacquer from the factory to help preserve the brass finish. They also may have accidentally gotten a coat of shellac or varnish if the door was refinished at any point in time while still being hung in the frame.

I'm with Whitt...Russwin made quality hardware, and pot metal seems to be too brittle to withstand the rigors of a heavy door. Plus, I don't even know if you could bend pot metal for the knuckles without it fracturing.

If you don't care about making a small scratch in an inconspicuous location (on back or in a screw hole), you could definitively prove they're brass if it reveals a shiny yellow mark.

 

They're brass.

Debora